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Glomerular Filtration Rate (GFR) — Pregnancy Reference Values

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Glomerular Filtration Rate (GFR)

Glomerular filtration rate reflects renal plasma filtration and increases substantially during normal pregnancy due to increased cardiac output and renal plasma flow. Standard creatinine-based estimated GFR equations are not validated in pregnancy.

Units Nonpregnant Female 1st Trimester 2nd Trimester 3rd Trimester
mL/min 106 – 132 131 – 166 135 – 170 117 – 182
Physiology in pregnancy
  • Renal plasma flow and GFR increase by approximately 40–50% by the first trimester.
  • This physiologic hyperfiltration leads to lower serum creatinine and urea levels.
  • GFR tends to plateau in the second trimester and may decline slightly late in the third trimester.
  • Measured creatinine clearance remains the most reliable quantitative estimate in pregnancy.
Causes of reduced GFR in pregnancy
  • Chronic kidney disease (diabetic nephropathy, glomerulonephritis, reflux nephropathy)
  • Preeclampsia and severe hypertensive disorders with glomerular endotheliosis
  • Acute kidney injury (prerenal, intrinsic, or obstructive)
  • Severe volume depletion (hyperemesis, hemorrhage, dehydration)
  • Sepsis or systemic illness causing renal hypoperfusion
  • Renal artery stenosis
  • Rare bilateral ureteral obstruction
  • Medication toxicity (NSAIDs, ACE inhibitors, ARBs — usually avoided in pregnancy)
  • Misinterpretation of creatinine-based eGFR formulas
Causes of elevated GFR
  • Normal physiologic hyperfiltration of pregnancy
  • High cardiac output states
  • Early diabetes mellitus with hyperfiltration
  • Obesity-related hyperfiltration
  • High protein intake
  • Recovery phase of acute kidney injury
  • Compensatory hyperfiltration in early CKD
Clinical obstetric considerations
  • Standard eGFR equations (CKD-EPI, MDRD) should not be used in pregnancy.
  • Small rises in serum creatinine during pregnancy are clinically significant.
  • Persistently reduced GFR increases risks of preeclampsia, fetal growth restriction, and preterm birth.
  • Third-trimester creatinine >0.9 mg/dL often signals underlying renal pathology.
  • Postpartum reassessment at 6–12 weeks is recommended for persistent abnormalities.

References

  1. Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies. Obstet Gynecol. 2009.
  2. Odutayo A, Hladunewich M. The renal physiology of pregnancy. Adv Chronic Kidney Dis. 2013.
  3. Cheung KL, Lafayette RA. Renal physiology of pregnancy. Clin J Am Soc Nephrol. 2013.
  4. Smith MC et al. Renal function in pregnancy. Nephrology. 2020.
  5. SMFM/ACOG Hypertensive Disorders Guidelines.